380 Quaiierly Journal of Coiichology. 



NOTE ON ABNOR^^IAL FORM OF CYLINDRELLA. 

 By J. T. MARSHALL. 



I think the abnormal form of C. Raveni noticed in the 

 Quarterly Journal of ConcJwIogy for May, by Mr. J. S. Gibbons, is 

 to be accounted for by a piece of grit or a small pebble filling up 

 the natural aperture and thereby necessitating the structure of 

 another mouth. I have observed it in species of Clausilia, and 

 also in the marine Lttlorina, though more rarely. In the latter 

 case I account for it by the periwinkle falling and getting wedged 

 in the crevice of a rock, when it v\'ould have to exercise its 

 ingenuity in constructing another mouth or submit to starvation. 



July, 1S77. 



NOTE ON A LIST OF SHELLS TAKEN AT 



GUERNSEY, &c. 



By J. T. MARSHALL. 



Will you allow me to point out an error in the otherwise 

 excellent paper contributed by Messrs. Cooke and Gwatkin in the 

 Quarterly Journal of Concholcgy {ox INL^ylast? They give Coch- 

 lodesnia pratcnue as occurring at Hcrm ; but this species has never 

 been met with in the Channel Islands, and what they probably 

 did find was Thracia pafyracea van villosiuscula, IMacgill. ( T. 

 tillosiuscula, F. & H.) The latter differs from T. p)-a;tenue mheing 

 much less depressed, not smooth or glossy, and in the absence of 

 the peculiar spoon-like ossicle or hinge which is characteristic of 

 T. pnitenue. It inhabits the coralline zone, and after a storm is 

 frequently cast up at Herm and other sandy beaches, as its fragility 

 and buoyany enable it to be easily transported. 



July, 187S. 



